Disclosed is a processor-implemented method for processing image data representing a document using an image processing apparatus. The processor receives image data, determines the classifications and counts of pixels in the image data (e.g., in device independent space that are degrees of neutral or non-neutral), classifies the image data into a category based on the determination of classifications and counts of pixels, and determines a billing structure for the image data based on the classification of image data. The classification can be performed on the image data prior to conversion into device dependent space. For example, by counting true color, neutral, non-neutral, and fuzzy color pixels and comparing them to thresholds, the image data can be classified as neutral or very colorful. By classifying images earlier in the image path, errors in billing are reduced.